What is the best way to burn fat and build muscle on a budget in regards to a diet and exercise?

Im an 18 year old 6'1 210lb male with hardly any muscle, my normal diet is pretty simple, junk, i drink nothing but soda, about a 24 pack of coke every 2 days, as far as food is concerned i eat things like corn-dogs and microwave burritos for dinner, i work third shift so its hard to plan meals as my girlfriend works days, most of the time i grab what i can, when im at work for lunch i buy 2 Monster energy drinks because the last few years i don't get very good sleep and don't have much energy, and its paired with things like chocolate chip cookies and Doritos i really need some help ive looked online but most things i found are either expensive, hard to cook because i don't know how and my schedule conflicts, or its not something i can just buy outright at lunch time at work, i work in Wal-mart so i have some options but im not sure what to get, now that ive covered food my lifestyle also comes into play, just about every night that im off work or when i get home in the morning i sit down and play video-games or mess around on the computer until i go to sleep, so other than work which im constantly walking and lifting(im a stocker) i don't get much exercise, and to make matters worse im a longtime smoker i used to smoke up to 2 packs a day but have cut down in the last year to a little over half a pack a day, please any help with advice on exercise, food or drinks, how to get my better sleep and energy back, I don't know if anyone can help with the smoking but ill throw that in as well, it would be greatly appreciated